This invention relates to an electrical connector for electrically connecting a printed circuit board to an electrical device, and, in particular to an edge connector for receiving a board edge portion of a printed circuit board to connect pads formed on a surface of the board edge portion to an electrical device such as another printed circuit board.
In a prior art, there is well known an edge connector of a type described above which comprises an insulator having a board receiving groove for receiving a board edge portion, and a plurality of contacts fixedly mounted in the insulator. The insulator is mounted on an electrical device to be connected with the printed circuit board. Each of the plurality of contacts is made of metal plate to have a fitting portion to be fixedly fitted to the insulator, a contact portion cantilevered at the fitting portion and extending to the board receiving groove, and a terminal portion extending from the fitting portion outside the insulator for connecting with the electrical device.
Under a condition where the electrical connector is mounted on the electrical device, when the board edge portion of the printed circuit is inserted into the board receiving groove, each of pads formed on the board edge portion comes into contact with the contact portion of each of the contacts. Thus, the printed circuit board is electrically connected to the electrical device through the contact between the pad and the contact.
In order to insure a reliable sufficient contact force between the pad and the contact portion, the contact portion is partially protruded into the board receiving groove so that the cantilevered contact portion is elastically deformed by the board edge portion inserted into the board receiving groove. The elastic recovering force of the deformation provides the contact force.
In the known edge connector, there needs any insertion force for inserting the board edge portion into the board receiving groove to deform the contacts. The insertion force is increased as the number of pads and contacts is increased, resulting in difficulty of the insertion of the board edge portion. Applicatton of large insertion force often deforms the printed circuit board to result in break of the printed circuit. Further, when the board edge is inserted into the board receiving groove, friction force is caused between the printed circuit board and the contact portion. This often results in wear of the printed circuit board itself and pads formed thereon.